The 5 kinds of sci-fi space travel, ranked by realism

• The entrance to a wormhole has often been represented as a tube, which makes sense given the name. But it’s also inaccurate. Interstellar, in one of its most intense scenes, got it right. From our perspective in 3-D space, a wormhole should look like a sphere.
• Wormholes are an attractive approach to FTL technology because they don’t require you to break the speed of light.
• Wormhole theory also allows for the possibility of traveling between universes. 

Warp technology is synonymous with the Star Trek series.

Like an Einstein-Rosen bridge, warp technology skirts around the impossibility of accelerating a ship past the speed of light. Instead, a warp drive bends space itself. It compresses space in front of the craft and expands it behind. The Enterprise is basically riding a bubble of regular 3-D space while the universe changes around it.

• Warp technology may be possible in reality.
• In 1994, theoretical physicist Miguel Alcubierre proposed a means of FTL space travel consistent with general relativity. Inspired by Star Trek, Alcubierre described an engine creating an energy field with lower density than the vacuum of space. By contracting space ahead of the ship and expanding it behind, a spacecraft could “ride a wave” forward.
• Unfortunately, Alcubierre's proposal raises the same theoretical problems as wormhole travel. Just as wormholes would require massive amounts of energy — and some as-yet unknown material to sustain it — so would warp drives.

Hyperspace is best understood as a sub-region of our real space where the same physical laws don’t apply. Hyperspace has no theoretical basis like Einstein-Rosen bridges or warp drives.

This universe doesn’t seem to allow faster-than-light travel. The solution: just don’t travel through our universe. In the Star Wars films, all kinds of ships are equipped with hyperspace drives, from small personal fighters like Poe Dameron’s X-wing, to larger freighters like the Millennium Falcon. Even that massive moon-sized space station, the Death Star, has a hyperdrive. In this case, “hyperspace” may merely be another name for lightspeed travel.

The Jump Drives in Battlestar Galactica made interstellar teleportation possible with virtually no delay. Both human ships and their Cylon counterparts used FTL drives. We were also told that when a ship jumps, it warps the space around it and can damage other nearby vessels.

As with hyperspace, jump drives apparently require complex calculations before and during a jump to avoid the risk of a ship materializing too close to a planet’s atmosphere — or within the planet itself.

For now, we’re a long way from teleporting people or jumping ships.

For 55 years, Doctor Who has chronicled the adventures across time and space of the Doctor and his/her human companions. Their means of transportation was a big blue box known as the TARDIS (Time and Relative Dimension in Space) that can take them anywhere, and anywhen, they want to go.

TARDISes are more magical than the tech of Star Trek. There does seem to be some sort of delay on the way — it’s more hyperdrive than jump drive. But essentially the TARDIS disappears here, flies through the Time Vortex, and reappears there. 

• In 2013, physicists Benjamin K. Tippett and David Tsang published a paper proposing a theoretical means of creating an actual retrograde-capable time machine: a way to travel to your own past. 
• Tippett and Tsang describe a bubble of spacetime containing a time-traveler entering a Closed Timelike Curve (essentially the same as an Einstein-Rosen bridge). Within that curve, the traveler can go anywhere on his or her own timeline, while within the bubble time seems to pass normally.
• The two physicists even theorized that timelike curves could be split and connected, opening up the possibility of traveling not just along your own timeline — but anywhere in time and space.